The mouth of any living creature is the most complex biomechanical system that provides it with nutrition, and hence existence. In higher organisms, the mouth, or, to put it scientifically, the oral cavity, carries an additional important load - sound pronunciation. The structure of the human oral cavity is the most complex, which was influenced by communication functions and a number of features associated with the development of the human body.
The structure and functions of the oral cavity
In all living organisms, including humans, the mouth is the first section of the digestive system. This is his most important and common function for most creatures, no matter what form nature has come up with. In humans, it is a gap that can open wide. We grab or take food with our mouth, hold it, grind it, abundantly wetting it with saliva, and push it into the esophagus, which is essentially a hollow tube through which food slips into the stomach for processing. But the beginning of digestion begins already in the mouth. That is why the ancient philosophers said how many times you live, how many years you live.
The second function of the mouth is the pronunciation of sounds. A person not only publishes them, but also combines them into complex combinations. Therefore, the structure of the oral cavity in people is much more complicated than that of our smaller brothers.
The third function of the mouth is participation in the breathing process. Here, his duties include only receiving portions of air and forwarding them to the respiratory tract, when for some reason his nose cannot cope with this and partially during a conversation.
Anatomical structure
Every day we use all parts of the mouth, and some of them even contemplate many times. In science, the structure of the oral cavity is somewhat concretized. The photo clearly shows what it is.
Doctors in this body distinguish two departments, called the vestibule of the mouth and actually its cavity.
In anticipation there are external organs (cheeks, lips) and internal (gums, teeth). So to say, the entrance to the oral cavity is called the mouth gap.
The oral cavity itself is a kind of space, on all sides limited by the organs and their parts. Below is the bottom of our mouth, above the palate, in front - the gums, as well as teeth, behind the tonsils, which are the border between the mouth and throat, from the sides of the cheek, in the center of the tongue. All internal parts of the oral cavity are covered with mucous membrane.
Lips
This body, to which so much attention is paid to the weaker sex, in order to rule the stronger sex, in fact, are paired muscle folds surrounding the oral gap. In humans, they participate in the retention of food entering the mouth, in sound formation, in mimic movements. The upper and lower lips are distinguished, the structure of which is approximately the same and includes three parts:
- External - covered with keratinized stratified squamous epithelium.
- Intermediate - has several layers, the outer of which is also horny. It is very thin and transparent. The capillaries shine through it perfectly, which causes the pink-red color of the lips. Where the horny skin layer passes into the mucosa, many nerve endings are concentrated (several tens of times more than at the fingertips), so the lips of a person are unusually sensitive.
- Mucous, occupying the back of the lips. It has many ducts of the salivary glands (labial). Its non-keratinizing epithelium covers.
The mucous membrane of the lips passes into the gingival mucosa with the formation of two longitudinal folds, called the frenulum of the upper lip and lower.
The border of the lower lip and chin is the horizontal chin labial groove.
The border of the upper lip and cheeks are nasolabial folds.
Between themselves, the lips are connected in the corners of the mouth with labial commissures.
Cheeks
The structure of the oral cavity includes a paired organ, commonly known as the cheeks. They are divided into right and left, each has an outer and inner part. The outer one is covered with thin, delicate skin, the inner non-keratinizing mucosa, which passes into the gingival mucosa. There is also a fatty body in the cheeks. In infants, it plays an important role in the process of sucking, therefore it is developed significantly. In adults, the fat body flattens and moves back. In medicine, it is called the Bisha fat lump. The basis of the cheeks are the buccal muscles. The glands in the submucosal layer of the cheeks are few. Their ducts open in the mucous membrane.
Sky
This part of the mouth is inherently a septum between the oral cavity and the nasal, as well as between the nasal part of the pharynx. The functions of the palate are basically just the formation of sounds. In chewing food, it participates insignificantly, since it has lost the clear severity of the transverse folds (in infants they are more noticeable). In addition, the palate enters the articulation apparatus, which provides a bite. There are palate hard and soft.
Solid accounts for 2/3 parts. It is formed by plates of the palatine bones and processes of the maxillary bones fused to each other. If for some reason splicing does not occur, the baby is born with an anomaly called a cleft palate. In this case, the nasal and oral cavities are not separated. Without specialized help, such a child dies.
The mucous membrane during normal development should grow together with the upper palate and smoothly pass to the soft palate, and then to the alveolar processes in the upper jaw, forming the upper gums.
The soft palate accounts for only 1/3 of the part, but it has a significant effect on the structure of the oral cavity and pharynx. In fact, the soft palate is a specific fold of the mucosa, like a curtain hanging over the root of the tongue. It separates the mouth from the throat. In the center of this “curtain” there is a small process called the tongue. It helps to make sounds.
Anterior arch (palatal-lingual) and posterior (palatopharyngeal) arch extend from the edges of the “curtain”. Between them there is a hole where an accumulation of cells of lymphoid tissue (palatine tonsil) is formed. 1 cm from it is the carotid artery.
Tongue
This body performs many functions:
- chewing (sucking in infants);
- sound educational;
- salivary;
- perceiving taste.
The shape of the tongue in a person is affected not by the structure of the oral cavity, but by its functional state. In the tongue, a root and a body are identified that have a back (side facing the palate). The body of the tongue crosses the longitudinal groove, and in the place of its connection with the root lies the transverse groove. Under the tongue is a special fold called the bridle. Near it are the ducts of the salivary glands.
The mucous membrane of the tongue is covered by a multilayer epithelium, in which there are taste buds, glands and lymph formations. The top, tip and lateral parts of the tongue are covered with dozens of papillae, which are divided into mushroom-shaped, filiform, conical, leaf-shaped, grooved in shape. There are no papillae at the root of the tongue, but there are clusters of lymph cells that form the lingual tonsils.
Teeth and gums
These two interconnected parts have a great influence on the structural features of the oral cavity. A person’s teeth begin to develop at the embryo stage. A newborn in each jaw has 18 follicles (10 milk teeth and 8 molars). They are located in two rows: labial and lingual. The appearance of milk teeth is considered the norm when the baby is 6 to 12 months old. The age when normal milk teeth fall out is even more extended - from 6 years to 12. Adults should have from 28 to 32 teeth. A smaller number negatively affects the processing of food and, as a consequence, the work of the digestive tract, since it is the teeth that play the main role in chewing food. In addition, they participate in proper sound production. The structure of any of the teeth (molar or milk) is the same and includes the root, crown and neck. The root is in the dental alveolus, at the end there is a tiny hole through which veins, arteries and nerves pass into the tooth. A person has formed 4 types of teeth, each of which has a certain shape of the crown:
- cutters (in the form of a chisel with a cutting surface);
- fangs (cone-shaped);
- premolars (oval, has a small chewing surface with two tubercles);
- large indigenous (cubic with 3-5 tubercles).
The necks of the teeth occupy a small area between the crown and the root and are covered by the gums. At its core, gums are mucous membranes. Their structure includes:
- interdental papilla;
- gingival margin;
- alveolar site;
- movable gum.
The gums consist of stratified epithelium and lamina.
Their basis is a specific stroma, consisting of many collagen fibers, which ensure a snug fit of the mucosa to the teeth and the correct chewing process.
Microflora
The structure of the mouth and oral cavity will not be fully disclosed if we do not mention the billions of microorganisms for which, during evolution, the human mouth has become not just a home, but the whole universe. Our oral cavity is attractive for the smallest bio-forms, due to its following features:
- stable, and optimal temperature;
- constantly high humidity;
- slightly alkaline environment;
- almost constant availability of nutrients in the public domain.
Infants are born into the world already with microbes in their mouths, which get there from the birth canal of women in labor for the shortest time, while the newborns pass them. In the future, colonization moves at an amazing rate, and after a month of microbes in the child’s mouth, there are several dozen species and millions of individuals. In adults, the number of species of microbes in the mouth ranges from 160 to 500, and their number reaches billions. An important role in such a large-scale population is played by the structure of the oral cavity. Only teeth (especially diseased and uncleaned) and plaque almost constantly present on them contain millions of microorganisms.
Among them, bacteria prevail, the leader among which are streptococci (up to 60%).
In addition to them, fungi (mainly candida) and viruses live in the mouth.
The structure and functions of the oral mucosa
From the penetration of pathogenic microbes into the tissues of the oral cavity, the mucous membrane protects. This is one of its main functions - the first to take on the blow of viruses and bacteria.
It also closes the mouth tissue from exposure to adverse temperatures, harmful substances and mechanical injuries.
In addition to the protective, the mucosa performs another very important function - secretory.
The structural features of the oral mucosa are such that glandular cells are located in its submucosal layer. Their clusters form small salivary glands. They continuously and regularly moisturize the mucous membrane, ensuring the fulfillment of its protective functions.
Depending on which departments the mucous membrane covers, it can be with a keratinized surface layer or epithelium (25%), with non-keratinized (60%) and mixed (15%).
Only the hard palate and gums are covered with keratinizing epithelium, because they take part in chewing and interact with solid fragments of food.
The non-keratinizing epithelium covers the cheeks, the soft palate, its appendage is the tongue, that is, those parts of the mouth that need flexibility.
The structure of both the one and the other epithelium includes 4 layers. The first two of them, basal and prickly, are both.
In the cornified, the third position is occupied by the granular layer, and the fourth by the horny layer (in it there are cells without nuclei and practically no leukocytes).
In non-keratinized, the third layer is intermediate, and the fourth is superficial. In it, an accumulation of white blood cell cells is observed, which also affects the protective functions of the mucosa.
Mixed epithelium covers the tongue.
The structure of the oral mucosa has other features:
- The lack of muscle plate in it.
- The absence of submucosa in certain parts of the oral cavity, that is, the mucosa lies directly on the muscles (observed, for example, on the tongue), or directly on the bone (for example, on the hard palate) and firmly fuses with the tissues located below.
- The presence of multiple capillaries (this gives the mucosa a characteristic reddish color).
The structure of the oral cavity in children
During a person’s life, the structure of his organs changes. Thus, the structure of the oral cavity of children under one year of age differs significantly from its structure in adults, and not only in the absence of teeth, as mentioned above.
The primary mouth of the embryo is formed in the second week after conception. Newborns, as everyone knows, have no teeth. But this is not at all the same as the lack of teeth in old people. The fact is that in the oral cavity of infants, the teeth are in a state of primordia, and, at the same time, both milk and permanent. At some point, they will appear on the surface of the gums. In the oral cavity of the elderly, the alveolar processes themselves are already atrophied, that is, there are no teeth and never will be.
All parts of the mouth in the newborn are created by nature in such a way as to ensure the sucking process. Typical differences that help to capture the nipple:
- Soft lips with a specific labial pad.
- A relatively well developed circular muscle in the mouth.
- Gingival membrane with many tubercles.
- The transverse folds in the hard palate are clearly expressed.
- The position of the lower jaw is distal (the baby advances its lower jaw, and performs its movements back and forth, and not to the sides or in a circular manner, as when chewing).
An important feature of babies is that they can swallow and breathe at the same time.
The structure of the mucous membrane of the oral cavity of infants is also different from adults. The epithelium in children under one year old consists only of the basal and spiky layers, and the epithelial papillae are very poorly developed. In the connective layer of the mucosa there are protein structures transmitted from the mother along with immunity. Growing up, the baby loses its immune properties. This also applies to the tissues of the oral mucosa. Subsequently, the epithelium thickens in it, the amount of glycogen on the hard palate and gums decreases.
By the age of three, in children the oral mucosa has more distinct regional differences, the epithelium acquires the ability to keratinization. But in the connective layer of the mucosa and near the blood vessels there are still many cellular elements. This contributes to increased permeability and, as a consequence, the occurrence of herpetic stomatitis.
By the age of 14, the structure of the oral mucosa in adolescents is not much different from adults, but against the background of hormonal changes in the body, they may have mucosal diseases: mild leukopenia and juvenile gingivitis.